Fermentative energy conversion: Renewable carbon source to biofuels (ethanol) using Saccharomyces cerevisiae and downstream purification through solar driven membrane distillation and nanofiltration

Abstract

Experimental studies on fermentative production of ethanol from renewable sugarcane juice as carbon source were carried out in a bench scale fermenter integrated with microfiltration, nanofiltration and membrane distillation units (MF-NF-MD) for downstream purification and concentration enrichment of ethanol. This new design is flexible, compact, eco-friendly, and modular and, operated in a cross flow module that ensures almost fouling-free membrane separation while overcoming the product inhibition of traditional batch fermenters. The system is blessed with steady and continuous ethanol production from sugarcane juice with comparatively high productivity 9.2gL−1h−1, yield 0.47gg−1 and concentration 54.3gL−1 using Saccharomyces cerevisiae (NCIM 3205) vis-à-vis the existing technologies. The new system enables continuous product withdrawal, separation and recycle of the biomass as well as residual carbon source back to the fermenter under high cell density without product inhibition. Membrane distillation in the final stage, increases product purity and results in significant concentration enrichment. The study culminates in development of a green and sustainable process for a biofuel production.